Analysis Of The Substation Grounding Grids By Finite Element Method

Based on 1-dimensional finite-element method coupled with 3-dimensional finite-element method, we make use of voltage-method of scalar quantity to analyze the grounding performance of the substation. Conductor parts of the grounding grid are analyzed with 1-dimensional finite-element method, and the soil parts are analyzed with 3-dimensional finite-element method. We introduce the coordinate transformation, and use normal hexahedron units to describe the earth area. The hexahedron, whose xy-plane is trapezoid, is transformed into cubic. The safety performance of the grounding grid at multilayer earth and the influencing factors such as grounding resistance and earth surface method are analyzed. Compared with the results of the calculations and the experiments from the EMC of North China Electric Power University, the presented method is proved to be effective. It reduces the number of units and speeds up the calculation obviously. The grounding grid performance at multilayer earth can be also effectively analyzed.